Showing papers on "Precision rectifier published in 1975"

Dynamic braking in controlled current motor drive systems

Abstract: A current source power converter for an electric motor is comprised by a combined controlled rectifier and chopper which is coupled to a controlled-current inverter by a dc reactor. In the motoring mode the combined rectifier and chopper functions as a phase controlled rectifier to control the current magnitude. In the dynamic braking mode a line switch is opened and a braking resistor placed across the rectifier output, and the combined rectifier and chopper is operated as a chopper to control the average voltage across the braking resistor and thus the current magnitude during braking.

Electronic switching circuits

Abstract: An electronic switching circuit for controlling the supply of alternating current to a load, comprising a bi-directional rectifier combination having first and second trigger electrodes; first and second direct current trigger voltage supplies of equal voltage but electrically isolated from each other; a first switchable semiconductor device connected in series between the first direct current trigger voltage supply and the first trigger electrode of the bi-directional rectifier combination; a second switchable semiconductor device connected in series between the second direct current trigger voltage supply and the second trigger electrode of the bi-directional rectifier combination; and control means for rendering the switchable semiconductor devices conductive from the next zero-voltage instant of the alternating current supply after the onset of a control signal. The control means may include a full-wave rectifier combination, a third switchable semiconductor device connected to receive a control signal on one input and the unsmoothed output waveform of the full-wave rectifier circuit on another input so that it will conduct only when the control signal is on and the rectifier output is substantially at zero voltage; and means for rendering the first and second switchable semiconductor devices conductive when the third switchable semiconductor device conducts. An optional additional circuit may be arranged to inhibit the control signal if the voltage of the full-wave rectifier circuit exceeds a threshold while the supply is switched on.

Fluid flow signal processing circuit

Abstract: A fluid mechanical arrangement of a bluff body flowmeter in a pipe line is disclosed with a thermal sensor arrangement for sensing flow signals in that pipe and with a method and circuit for processing the sensed signals to subtract low frequency fluid noise signal that accompany sensed signal and extracting sensed signals related to the fluid flow rate through the pipe. Signal processing is achieved through a circuit comprising an inverting amplifier, peak detector, summing amplifier and trigger amplifier. The detector senses positive and negative peaks of the thermal sensed flow signals and produces signals the frequency of which corresponds to the flow rate of fluid through the pipe. The detector also generates negative and positive peak indicating signals and stores them in combination with an output image of the thermistor sensed fluid flow signal. The inverting amplifier inverts the thermal sensed signal for driving the peak detector. The summing amplifier sums the thermal sensed signal with the signals stored by the peak detector and produces a resultant output signal which has a frequency corresponding to the flow rate through the pipe and which substantially excludes any component of the low frequency noise. The trigger amplifier converts the summing amplifier output signals into trigger pulses for a utilization means.

Voltage and temperature compensated linear rectifier

Abstract: An improved circuit for compensating for temperature and current variationsn rectifier circuits used for converting alternating current to a proportional direct current, particularly at low voltages. A separate rectifier to be used as a circuit standard is maintained in close thermal proximity to other rectifiers as part of the conversion circuit. A voltage proportional to that across the standard is applied as a bias to a terminal of the circuit rectifiers to automatically compensate for temperature and current changes in the circuit and thereby provide a more accurate rectification of an input voltage.

Gating signal control for a phase-controlled rectifier circuit

Abstract: A method and apparatus for controlling the phase retard time of a phase-controlled rectifier circuit in a power conversion system wherein a clock-pulse synchronized alternating voltage source is connected to supply power to the phase-controlled rectifier circuit. The clock pulses controlling the voltage source are detected and delayed for a predetermined time interval prior to their application to the voltage source. A ramp voltage generator synchronized to the clock pulses and a comparator circuit for comparing the ramp voltage signal level to a reference level provide a means for generating gate pulses to control the phase retard time of the phase-controlled rectifier circuit between maximum and minimum retard times. Maximum retard time is established at the occurrence of a clock pulse by applying a gating signal to the rectifier circuit if the rectifier circuit has not been triggered prior to detection of the clock pulse. Further gating signals are inhibited until the alternating voltage source has reversed polarity in response to the delayed clock pulses thus establishing a minimum retard time. The predetermined time interval between detection of the clock pulses and application of the delayed clock pulses to the alternating voltage source is selected to be at least sufficient to allow commutation and achievement of forward voltage blocking ability, by the components of the phase-controlled rectifier circuit.

Speed control means for AC motor

Abstract: An unbalanced switching circuit is connected with a bi-directional control rectifier in such a manner that variance of counter electro motive forces produced by rotation of an AC motor affects the lower switching voltage in the unbalanced switching circuit through diodes and a capacitor to increase or decrease the conduction angle of the bi-directional control rectifier.

Pulse interference blanking circuit for radio receivers

Abstract: After a preliminary differentiation, the demodulated signal is supplied in parallel to a peak rectifier and to a second differentiating network, the outputs of the latter two circuits being added in the input circuit of a switching transistor that controls the blanking gate of a receiver. The value of the resistor across the output capacitor of the peak rectifier, as well as the rectifier capacitor, is so chosen in value that periodically recurrent pulses that may be persistently present in the signal build up a blocking bias on the switching transistor reducing its sensitivity and preventing corresponding differentiated pulses from switching it on, whereas occasionally or irregularly appearing pulses develop a negligible bias through the rectifier, so that their twice differentiated derived pulses will switch on the transistor and produce blanking.

Circuit for generating synchronization signals

Abstract: A circuit for generating synchronization signals from a digital data pulse train having a bit period T and conveying pulses in non-return-to-zero form. The circuit comprising (i) a rectifier device arranged to fullwave rectify the digital data pulse train, (ii) an oscillatory circuit tuned to oscillate with period T and stimulated by the transitions of a waveform produced by the fullwave rectifier device and (iii) a peak detector arranged to produce a bias signal which is proportional to the amplitude of the output of the oscillatory circuit. The bias signal being active upon the fullwave rectifier device to stabilize the amplitude of the waveform produced by the oscillatory circuit.

Design of precision rectifiers using operational amplifiers

Abstract: Two new precision rectifiers, a halfwave circuit and a full wave circuit, are described. The circuitsemploy operational amplifiers to eliminate the effects of diode nonlinearity and diode-temperature dependence. The transfer characteristics of the two circuits are derived by analysis. Experimental results are also provided which show that the circuits operate accurately over a large dynamic range of input signals.

Signal quality evaluator

Abstract: In an arrangement for evaluating an incoming speech signal to enable the selection of a receiver with the best quality speech signal over a substantial range of input signal levels, the logarithm of the input signal is processed in an absolute value and filter circuit to obtain the envelope of the logarithm of the input waveform which is next applied to a peak detector and to a valley detector. The output voltage of the peak detector is proportional to the logarithm of the speech peaks, and the output voltage of the valley detector is proportional to the logarithm of the noise floor voltage during the speech pauses. The peak and valley detector output voltages are applied to an arithmetic circuit which provides a voltage that is a function of the ratio of the speech peaks to the intersyllable noise floor.

Fast automatic gain control circuit with adjustable range

Abstract: An automatic gain control circuit has its a-c signal input terminal connected directly to the numerator input of an analog divider, and connected through a peak detector to the denominator input of the analog divider. The quotient terminal of the analog divider provides a gain-controlled a-c signal output. The AGC circuit produces a constant amplitude output signal so long as the amplitude of the input signal exceeds an adjustable reference voltage applied to the peak detector. The reference voltage may be changed to change the range of input voltages resulting in a constant-amplitude output. The AGC circuit responds almost instantly to control a sudden increase in input voltage.

Automatic control device for an electronic flash apparatus

Abstract: A device for automatic control of the quantity of light from an electronic flash tube including a silicon controlled rectifier connected in series with the flash tube, a circuit for applying a reverse voltage between the main electrodes of said silicon controlled rectifier so as to open said rectifier, and a switching element connected between said reverse voltage applying circuit and said silicon controlled rectifier. Responsive to the output signal from the reverse voltage applying circuit, the switching element short-circuits the gate electrode and cathode of the rectifier. With this arrangement, it is possible to decrease the capacity of a commutation capacitor constituting part of the reverse voltage applying circuit.

Smoker's lighter

Abstract: An electrically-ignited gas lighter with a capacitor discharge ignition circuit is provided with a blocking oscillator and an oscillation transformer to increase the level of the voltage from a single silver oxide battery of 1.5 volts to a higher level of at least 100 volts for charging the storage capacitor through a half-wave rectifier. A triggering circuit is provided to discharge the storage capacitor automatically and periodically through a silicon controlled rectifier at a predetermined voltage.

In line rectifier assembly

Abstract: A self-mountable, self-contained and encapsulated rectifier assembly operative to provide a high D.C. voltage at low current while minimizing arcing, corona and other disruptive electrical phenomena.

Method for triggering a controlled rectifier and for keeping it conductive and a generator for that purpose

Abstract: A method of triggering a controlled rectifier to ensure that it conducts fully and remains conducting for a required time, comprising supplying to the control electrode of the rectifier a large amplitude pulse with high transductance per unit of time to initiate conducting, and a small amplitude signal to maintain conducting. A circuit for producing such a pulse and signal comprises a pulse generator and a blocking oscillator both controlled by a control generator.

Condition detector circuit

Abstract: A flame monitoring circuit in which a storage capacitor is connected between the "hot" line of an a.c. power supply and a flame electrode disposed so as to be bathed in the flame being monitored. Because of its rectification properties, the flame causes a flow of direct current that charges the storage capacitor providing a flame indicating signal voltage. A control circuit powered by the a.c. source is coupled to the storage capacitor so as to respond to either the presence or absence thereon of a d.c. signal voltage. Electrically coupling the storage capacitor and the control circuit is a sampling circuit for periodically sampling the energy level stored in the storage capaitor. The sampling circuit includes a discharge capacitor coupled to the storage capacitor so as to receive charging current therefrom and a complementary silicon-controlled rectifier is periodically activated to dump the energy from the discharge capacitor into the gate circuit of a silicon-controlled rectifier in the control circuit. The complementary silicon-controlled rectifier is fired at zero-crossings of the a.c. power source immediately preceding those half cycles during which flame rectified current is produced.

X-ray diagnostic generator

Abstract: An X-ray diagnostic generator in which the voltage demands on the rectifier in the high-voltage circuit are essentially lower than in the present state of the art in that the circuit arrangement is located in the primary circuit of the high-voltage transformer. The circuit arrangement for the automatic determination of the starting timepoint for the X-ray tube may be arranged in the primary circuit of the high-voltage transformer, so that the rectifier in the secondary circuit thus serves only for effecting the regulation of the X-ray tube voltage. Consequently, in this instance, the rectifier need be dimensioned for only a voltage which is obtained from the fluctuations of the X-ray tube voltage.

Method and apparatus for current regulation of a circulating-currentfree rectifier circuit arrangement

Abstract: A method of and apparatus for the current regulation of a circulating-currentfree or loop-currentfree rectifier circuit arrangement, especially for an anti-parallel circuit, wherein the operating point for firing a rectifier arrangement after switching is continuously controlled or readjusted. The firing angle-control voltage of the non-fired rectifier arrangement is derived from the firing angle-control voltage of the fired rectifier arrangement and the course as a function of time of the armature current of a motor constituting the load.

Rectifier monitoring circuit

Abstract: Each of a plurality of parallel power supplies is connected to a common load via a coupling diode. The voltage across the coupling diode is monitored as well as the peak conducting voltage across the supply rectifier devices. A comparator is responsive to the monitored coupling diode voltage exceeding the monitored rectifier device conducting voltage to produce an alarm signal indicative of the supply not being coupled to the common load through the coupling diode.

Signal peak in a signal train recognition method - has signal level of a chromatogram affected with an interference level

Abstract: A peak detector delivers a signal when the test signal, or a signal derived from it, exceeds or does not reach a threshold. The threshold is derived from the noise effected signal itself by filtering, amplification and rectification. Frequencies appearing in the test signal with a low level only are filtered out by a high-pass filter and amplified, and are after their rectification made available in the peak detector as the threshold or its component. the circuit comprises a high pass filter, an amplifier a rectifier, an earthed capacitor, a resistance voltage divider and two comparators each with a direct connection line to the input.

Apparatus for pulsed arc welding and building-up of articles

Abstract: The proposed apparatus comprises an arc-welding source, including a current pulse generator with a control circuit and a rectifier. A choke at the output of the rectifier is connected to the electrode-article gap, in series with the rectifier of the pulse generator. The rectifier is a fullwave rectifier and comprises two controlled thyristors and two uncontrolled diodes. As the apparatus is in operation, one of the thyristors becomes conducting during each alternating current half-cycle. Current pulses pass through the arc and choke and are added to the pedestal of the current that continuously flows from the rectifier through the welding circuit.

DC power supply cct - uses bridge rectifier to provide DC within stipulated range from two possible AC inputs

Abstract: The mean amplitudes of the two given possible a.c. supplies lie in an approximate ratio of 1:2 which practically means 110 and 220 volt mains supplies. A switching circuit is installed in one branch of the bridge rectifier. A threshold value switching circuit controlled by the a.c. is provided. It is connected to the bridge rectifier in such a manner that when a stipulated voltage value, lying between the two possible a.c. supplies, is exceeded the bridging branch of the rectifier is disconnected. In the lower range, e.g. 110V, bridge rectification is provided, i.e. for both half-waves, while in the upper, e.g. 220v, one way rectification is provided, i.e. for upper or lower half waves.

Async. generator excitation cct - has star-coupled excit windings broken at neutral point and bridge rectifier for smooth regulation

Abstract: The asynchronous generator's excitation circuit has the generator's star-coupled excitation windings (3) broken at their neutral point (11) and a bridge rectifier (12) inserted. The rectifier is coupled to a capacitor (14) bridged by an SCR (15). The SCR is controlled from the amplified output of the comparator (21) that compares the generator's actual output voltage with reference voltage representing the required output voltage. The other ends of the excitation windings are coupled to the load and to another bridge rectifier that forms the supply for the reference voltage circuit and simultaneously provides a measure of the generator's output.

Control system for rectifier equipment

Abstract: A control system for a rectifier unit for high voltage direct current transmission includes a control pulse emitter for the valves of the rectifier unit and a regulator for setting the control angle of the control pulse emitter. A signal limiter is provided on the output side of the regulator for limiting the control signal in response to an increase of the voltage of the rectifier unit towards a smaller control angle. The control system is provided with an arrangement which senses the control angle of the control pulse emitter, such arrangement being connected to the signal limiter in such a way that the upper limit of the magnitude of the control signal decreases with a decreasing control angle.